Authorities on Monday appealed for the public's help in finding pet owners who hired a Houston man posing as a veterinarian and whose treatment may have imperiled animals.

Over the past year, police say at least 50 pets were treated by 26-year-old Wilfredo Gutierrez, who may have offered improper medications, vaccinations and procedures.

He has pleaded guilty to the unlawful practice of veterinary medicine, a misdemeanor, and has been charged with felony drug possession for having morphine that authorities believe was stolen from his employer or acquired via the internet.

The veterinary technician, who worked at an undisclosed Houston veterinary office, operated independently as DogSmart Veterinary Services, Wilfredo Gutierrez Pet Services and Mobile Vet Vaccinations. He went to residences - mostly in northwest Houston - to examine dogs and cats, but also retrieved animals for spay and neuter services then returned them.

Authorities are not sure if any animals died because of the fake vet's treatments.

"We have learned that there are probably over 50 known victims and we are afraid that there are many more victims whose pets have been treated by this individual," Senior Police Officer Suzanne Hollifield, who works with the Houston Police Department's animal cruelty unit, said during a news conference on Monday in which authorities sought assistance from others who used the imposter veterinarian.

"If you believe that your pet has been treated by Wilfredo Gutierrez, then we really encourage you to take your animal to a licensed veterinarian," Hollifield said.

The scheme to mislead pet owners was cracked when neighbors called police about a crippled dog on Houston's northwest side who was not receiving proper medical attention. When Hollifield visited in May, the owner said the animal was examined by Gutierrez, who placed an elastic bandage on what turned out to be a broken leg.

Suspicious, Hollifield investigated further, then contacted the Texas State Board of Veterinary Medical Examiners to join an undercover operation.

The agencies lured Gutierrez to examine a dog with a minor skin condition.

"For our animal, he was going to dip the dog, prescribe it some oral medications and he was also going to vaccinate the dog," Hollifield said. "He was going to charge $150 for all those services."

Gutierrez crossed the line, she said, when he provided a diagnosis and recommended a treatment.

He was arrested July 16 on the unlicensed practice charge, pleaded guilty two days later and received a two-day sentence. Gutierrez remains in the Harris County jail on a felony drug charge following the HPD crime lab's confirmation that the controlled substance he possessed during the sting was morphine, court records show.

According to Hollifield, Gutierrez told investigators that "he loved animals and he just wanted to take care of them."

The HPD investigation revealed the illegal enterprises were additional sources of income for Gutierrez, who advertised, but largely ran a "referral business," Hollifield said.

"He was charging a significantly less amount of money from a licensed veterinarian and all of the victims that I have talked to so far said that is the main reason that they used him," the officer said.

Authorities are continuing the probe and do not know where animal operations were performed. Hollifield said Gutierrez could face additional charges.

Vet technicians in Texas are not required to be licensed by the state or certified by a veterinarian trade group.

Nicole Oria, executive director of the Texas State Board of Veterinary Medical Examiners, said most unlicensed practice cases are groomers who administer vaccinations or people posing as doctors of veterinary medicine.

The agency has clocked 42 such cases this fiscal year, which ends on Aug. 31, and has the authority to send cease and desist letters to offenders, Oria said. The administrative penalty is not an admission of guilt, she added.